New Gluten Threshold Study from Australia

In Brief: A Randomized Double-Blind, Placebo-Controlled Dose-Response Study to Assess the Gluten Threshold Dose in Celiac Disease was conducted by a team of researchers from Australia and recently published in the journal Gastroenterology. A primary goal of the research was to determine the minimal dose amount of gluten required to cause an immune response–specifically an interleukin-2 (IL-2) response in adults with celiac disease adhering to a gluten-free diet.

Among other objectives, the researchers looked at the lowest observed immune effect level (LOIEL), defined as the lowest gluten dose that an immune effect is observed in any study participant during a controlled challenge, and the no observed Immune effect level (NOIEL) defined as the highest gluten dose at which no immune effect is observed. The LOIEL in the current study was 3 mg. The NOIEL was 2 mg.

The lay summary for this research is, “Low doses of gluten below currently accepted international food regulations result in immune activation in some patients with celiac disease.” However, the researchers stated that “the long-term clinical consequences of such low-dose immune activation remain unknown, and it is not yet established whether an acute IL-2 response to a specific dose of gluten predicts histological damage or complications with chronic exposure to the same dose.” In other words, more research is needed.

Putting the LOIEL and NOIEL in perspective

Each one-ounce amount of gluten-free food containing a 20 parts per million level of gluten contains approximately 0.56 mg of gluten. To stay below the LOIEL of 3 mg, no more than 5.4 ounces could be eaten.

Each one-ounce amount of gluten-free food containing a 10 parts per million level of gluten contains approximately 0.29 mg of gluten. To stay below the LOIEL of 3 mg, no more than 10.3 ounces could be eaten.

Each one-ounce amount of gluten-free food containing a 5 parts per million level of gluten contains approximately 0.18 mg of gluten. To stay below the LOIEL of 3 mg, no more than 16.7 ounces could be eaten.

How do foods generally test at Gluten Free Watchdog?

In 2025, 92% of labeled gluten-free foods tested by GFWD tested below 5 parts per million* of gluten.

*Five parts per million (5 mg/kg) is the lowest level of gluten that can be quantified using the scientifically validated R5 ELISA.

Bottom line

Over the 15 years that we have been testing gluten-free products at Gluten Free Watchdog, the vast majority tested below 5 parts per million of gluten. This is regardless of the FDA regulation of less than 20 parts per million of gluten for labeled gluten-free foods.

More study information

For take-aways from the researchers, see https://www.wesleyresearch.org.au/australian-study-shows-smallest-gluten-dose-triggers-coeliac-patients/

The full text of the article can be accessed by clicking on pdf at https://www.gastrojournal.org/article/S0016-5085(26)00264-7/fulltext